At the onset it may helpful to the understanding of the present invention to define the terms “phakic” and “aphakic” as related to human eyes. The term “phakic” is applied to an eye in which the natural ocular lens is still present. This is in contrast to an “aphakic” eye from which the natural ocular lens —or any reason—has been removed. A phakic eye is considered a dynamic or active eye because the living natural lens is subject to change over time, while an aphakic eye is considered a static eye.
One relatively common ocular problem is impaired or complete loss of vision due to the natural ocular lens becoming cloudy or opaque—a condition known as cataract. The formation of cataracts is typically associated with natural bodily aging, and most individuals over the age of about 60 years suffer from cataracts at least to some extent.
Cataracts cannot currently be cured, reversed, or even significantly arrested. Accordingly, the corrective action involves surgically removing the natural lens when the lens becomes so cloudy that vision is greatly impaired, the result being that a phakic eye becomes an aphakic eye.
After a defective natural lens has been surgically removed, the current vision-restoring practice (since about the 1940's) is to implant in the aphakic eye an artificial refractive lens called an intraocular lens (IOL) having an optic and optic fixation means. Previously, thick, heavy, high diopter spectacles were prescribed for aphakic eyes. Such spectacles however were and still are generally disliked by most patients for their weight and appearance.
Implantable IOLs were initially constructed from rigid polymethyl methacrylate (PMMA), a hard, biocompatable plastic material. More recently, IOLs have been constructed from a soft, elastically deformable, silicone or acrylic material that enables insertion of the IOLs through small ocular incisions.
In addition to the implanting of IOLs in aphakic eyes to restore vision after removal of the natural lens, considerable interest has recently arisen in implanting IOLs in phakic eyes to correct myopia, hyperopia, presbyopia or astigmatism problems associated with non-cataract natural lenses. This implanting of corrective IOLs in phakic eyes is an often-attractive alternative to the wearing of corrective spectacles or contact lenses, which limit certain activities and even certain professions, or having performed such surgical procedures on the cornea as radial keratomy (RK) or photo-radial keratectomy (PRK), which may not be desired by many individuals for various reasons. The implanting of refractive IOLs in phakic eyes to correct vision problems is considered to constitute one of the remaining frontiers of vision correction.
In an aphakic eye, a replacement IOL is now typically implanted in the posterior chamber of the eye from which the natural lens has been removed. In contrast, a corrective IOL for a phakic eye is most desirably implanted in the anterior chamber of the eye, forwardly of the intact natural lens remaining in the posterior chamber of the eye. (In some difficult cases, however, an IOL may be implanted in the anterior chamber after the natural lens has been removed from the posterior chamber.) The former type of IOL is called a posterior chamber IOL and the latter type is called an anterior chamber IOL. There are significant construction differences between these two types of IOLs.
With specific regard to anterior chamber IOLs (with which this application is concerned), there has been recently renewed interest in IOLs constructed for fixation to the iris for correcting vision in phakic eyes (although, some of the earliest IOLs for aphakic eyes were iris fixated anterior chamber IOLs). One reason for renewed interest in iris fixated IOLs for phakic eyes that fixating (i.e., attaching) the optic supporting structure directly to the iris itself avoids contact by the IOL with the sensitive filtration angle of the eye, thereby reducing subsequent ocular problems.
Iris fixated IOLs are disclosed in recent U.S. Pat. Nos. 4,215,440 and 5,192,319 to Jan Worst. Both of such patents disclose IOLs employing one or more optic fixation members formed having a pair of pincer arms which, by surgical manipulation when attaching the IOLs to an iris, pinch up and hold a small, anterior surface region of the iris in the narrow gap between the pincer arms. This pinching action detachably attaches the IOL to the iris so that the IOL optic is (ideally) fixated in the region of the iris opening (i.e., the pupil of the eye).
However, the present inventor considers that improvements to the iris fixated IOL designs disclosed in the two above-cited Worst patents are desirable. It is, therefore, a principal objective of the present invention to provide such improvements, particularly in the areas of improving optic centration and enabling small incision implanting of iris fixated IOLs.
Moreover, so far as is known to the present inventor, the attaching to the anterior surface of the iris of iris fixated IOLs of the type disclosed by the above-referenced Worst patents has involved a very tedious and difficult two-handed procedure requiring great skill, dexterity and training.
In this regard, a forceps is used by one of the IOL-implanting surgeon's hand to hold the IOL with the IOL optic centered on the iris. The surgeon uses his other hand to manipulate a needle (called an enclavation needle) to capture and lift a small region of iris stromal tissue adjacent the gap between the pair of pincer arms of one of the IOL fixation members (haptics).
This lifting of iris tissue in the gap region lifts opposing end regions of the pincer arms, thereby causing widening of the gap between the pincer arms. Thus, when the tip of the enclavation needle is withdrawn from the iris tissue, the lifted region of tissue becomes pinched in the narrowing gap between the pincer arms as the arms flex back downwardly to their normal position. This procedure results in the attachment of the related IOL fixation loop to the iris.
As a next step, the forceps and enclavation needle are switched between the surgeon's hands to perform the same attachment procedure for the second IOL fixation loop to the iris and the resulting attachment of the IOL to the iris.
This two-handed (i.e., bi-manual) IOL-to-iris fixation procedure is not only extremely difficult and very dependent upon the surgeon's skill, but it does not leave a free hand of the surgeon to perform other, ancillary procedures associated with the surgical implant of the iris fixated IOL.
In the parent application of the inventor, an iris fixated intraocular lens and an instrument for attaching same to an iris is described. The instrument is a combination enclavation needle and forceps instrument capable of one-handed use. In the implantation of an IOL, the forceps grips a portion of the haptic and the enclavation needle draws a small portion of the patient's eye material into a pincer gap disposed within the haptic. There is a problem, however, with respect to the instrument described in the inventor's parent application. That problem arises from the fact that the physical orientation of the enclavation needle and the forceps portions of the combination instrument is fixed with respect to each instrument. Either the enclavation needle is disposed above the forceps or the enclavation needle is disposed below the forceps instrument. It follows from this fact that a practitioner can only use a single combination instrument to fix that haptic of an IOL whose orientation corresponds to the orientation of the instrument. Since the practitioner must fix both haptics of the IOL by insertion of a combination instrument through a single incision in the eye of the patient, the practitioner can only attach a haptic of the IOL to the patient where the haptic has an orientation which corresponds to the orientation of the instrument. Thus, to attach a haptic to the IOL which has a reverse orientation, the practitioner must use a combination instrument having such reverse configuration. This means that a practitioner is required to purchase and maintain two separate combination instruments each having opposite orientations of enclavation needle and forceps. This presents a significant cost disadvantage to the practitioner.
Accordingly, there is a need for an intraocular lens capable of being installed by a single combination enclavation needle and forceps instrument.
In the various FIGS., the same elements and features are given the same reference numbers. In the various variation variations, corresponding elements and features are given the same reference numbers as first set forth, followed by an “a”, “b”, “c”, and so on, as appropriate and/or as will be evident in the following DESCRIPTION.